Thx to Mark Harrison

UGS contains one of the nicest web part collections I've seen:

Breadcrumbs - Fairly standard.

Connected Page Viewer - More IFrame attributes than the Page Viewer, and works with connected web parts.

Event Rollup - Aggregate calendars from subsites. Nifty!

Flash Movie - Just what it says, clean implementation.

Google Search - Displays results in-place, and can be configured to search a particular site.

Google Translator

Importable WebParts

Outl2TccSyncer - Much potential, the goal is to synchronise Outlook and SharePoint calendars.

Poll - Looks more like what you're used to than the built-in survey.

QuickTime Movie - Just what it says, clean implementation.

RateThisPage - Short and sweet, again more like what you're used to.

Ressource Plan

Site Navigation - Clean display, and many display options (from root, from child, etc.)

TccFeeder

TccRoleSyncer

User Alerts - Lets an administer add, remove or change alerts for any site user. One way to push alerts rather than wait for users to subscribe.

Welcome - Display personalised welcome messages.

What's new - A concise list of New items on a team site.

World Time - If your users work in different time zones, it helps to show clocks for each.